Furnace



Nov. 7, 1950 J, WEBER 2,528,564

FURNACE Filed Nov. 29, 1943 2 Sheets-Sheet 1 L. J. WEBER Nov. 7, 1950 FURNACE N.. GU.

2 Sheets-Sheet 2 M Il 5 lL INVENTOR L. J. WEBER l Filed Nov. 29. 1943 AT1 lo Patented Nov. 7, 1950 FURNACE Louis J. Weber, Borger, Tex., assignor to Phillips Petroleum Company, a corporation of Dela- Application November 29, 1943, Serial No. 512,284

4 Claims. 1

This invention relates to an improved design of furnace used for preheating or cracking petroleum products and other fluids.

My continuation-in-part application Serial No. 666,383 was filed on May 1, 1946 copending with the present application to show additional features not disclosed in the present application.

It is an object of the invention to provide a .simple and efficient furnace unit, which can be constructed on less ground space, and with the use of less critical materials than required by conventional designs.

It is a further object of the invention to provide a satisfactory and efficient furnace, using less structural and plate steel, less concrete, brick and other materials than other furnaces of the same duty now in use.

It is a still further object of the invention to dispose the heat absorbing surface in the most advantageous manner with respect to the radiant surface in the rebox, and to fully utilize the furnace radiant heat surface and to control the rate of heat input to the tube coil.

Other objects and advantages will be apparent from the detailed description to follow and the included drawings of which,

Figure l is an end sectional view through one half of the furnace and the other half of the furnace is shown in elevation;

Figure 2 is a sectional view through another embodiment of the furnace; and

Figure 3 is a side elevational view of the furnace embodiment shown in Figure 2.

Referring to Figure 1, the furnace tubes 'are separated into two main groups, convection tubes represented at I and radiant tubes consisting of the floor tubes 2, slanting-roof tubes 3 and verticalsidewall tubes 4. The convection tubes I are supported by passing through holes in end plates Ia, the end plates in turn being secured to and supported by vertical columns I4. (This method of supporting the tubes in the convection section is old in the art, being shown in Figure 1 of Primrose 1,758,239 (1930) who supports tubes 24 by end plates 21.) There are four central framework columns I4 disposed at the corners of an imaginary rectangle, and columns I4 also support the two principal beams 8 which run entirely across the furnace and which in turn support the furnace stack I0. Slanting-roof beams I3 are supported at their outer ends on top of vertical beams I I. Beams I I are also called buck stays, or outer framework columns. The inner ends of beams I3 are secured to and supported by principal beams 8. Beams I3 may be connected to beams II and 8 by any suitable means, such as the usual riveting or welding of beams together, the entire manner of supporting the stack I and the roof beams I3 being old in the prior art and shown in Figure 1 of the patent to Coghill 2,121,537 (1938). As is usual in such furnaces the lire box arch brick work I1 and the roof covering I2 are secured to and supported by beam I3 by conventional connection means i not shown) and the refractory fire brick Walls I5a are similarly connected to the buck stays II. The entire structure is supported upon a suitable refractory base such as a concrete foundation IIa having floor tube supporting ribs I5. The roof tubes 3 and vertical wall tubes 4 are supported by means of alloy castings B attached to the beams I3 and buck stays II, respectively, by conventional means (not shown).

Suspended from the main beams 8 by conventional means (not shown) are the refractory bridgewalls 6 which, as illustrated, are hollow, forming vertical passages 8a, and are open at the ends, as indicated at A (Figure l) so that air from the outside may enter them and flow upwardly through passages 8a and be discharged into the windboxes 9. The burners 5 open into the furnace in a direction to impinge their flames on the bridgewalls 6.

The bridgewalls 6 are in the form of suspended curtains. The refractory walls themselves are composed of re brick tile attached to this curtain in any suitable and well known manner, as by means of hanger castings commonly used for similar purposes. As shown, the lower ends of the bridgewalls 6 are provided with transverse projections 'I so that flue gases are given a turbulent motion beforel enteringr the convection tube bank I. The proiections l serve further to assist in bringing all radiant surface within the fire box to a radiant uniform temperature and thereby insure uniform heat radiation.

The hollow bridgewalls 6 extend all the way across the furnace and being spaced as shown in Figure 1 form a vertical passage in which the convection tube bank I is mounted and opening directly into the stack I8. Also as is clear from Figure l, the lower ends of the bridgewalls are vertically spaced from the foundation or base of the furnace so that the flue gases can pass to the stack between the bridgewalls as indicated by the arrows in Figure 1. The bridgewalls being unattached at the ends of the outer walls of the furnace are truly suspended curtains capable of any necessary movement to allow for expansion and contraction thereof.

In the operation of this furnace structure, the furnace feed of the fluid to be heated enters at the top of the convection tube bank I and progresses downwardly to the floor tubes 2, thence to the roof tubes 3 and vertical wall tubes 4 and thence to the outlet 2i) from the furnace. The sequence of flow may be changed to suit desired heating characteristics. The burners fire at an angle against the air cooled bridgewall, from which the heat is radiated to the tubes. The construction of the bridgewall is such that full effect of the radiant heat is not directed on tion tube bank I' to the stack 1'.

vfloor tubes, protection 'being afforded by the projection 1. This feature of the design makes the floor tubes 2 in reality a secondary preheating zone. By properly arranging the sequence of feed flow the rate of heat input to the material can be closely controlled. l

Air preheat to the burners is secured in the following manner: cold air enters the bridgewall cavity 8 through openings A (Figure 1) in the end panels of the furnace. The air is heated within the bridgewall, at the same time cooling the bridgewall steel to safe operating limits, and passes upward to burner windbox 9 where it enters the burners 5,. The length of the air passages is short, which makes the draft loss low and permits the use of a low flue gas stack.

Figures 2 and 3 show the second design of furnace with l' indicating the convection tubes, slanting roof tubes at 2', vertical wall tubes at 3 and slanting floor tubes at 4'. Since the furnace is of the double chamber two coil type, both halves are identical as in the case of Figure l. Burners 5' are opposite the air cooled suspended bridgewall which includes the Ibeam i6' as a part of its structure. The air passage 8a communicates with openings in the end walls and roof as shown in Figure 2. The stack l' is supported by beams 8 which also support the suspended arch 9 and the roof covering i0. The concrete floor il is supported by piers i5 which also support buckstays i3'. The oor tubes d' are supported by refractory piers I2' resting on the concrete slab.

In operation, the furnace feed of the uid to be heated enters at the top of the convection tube bank I' and progresses downwardly to the floor tubes 4', then to the wall tubes 3', thence to the heat distribution around the tubes and between different tubes. The ue gases pass under the suspended bridgewall and up through the convec- The concrete oor slab i I is prevented from becoming too hot by being air cooled on the bottomside. The rai diant bridgewall 6' is cooled by air which enters at the furnace ends, passing into the space between the walls and thence upwardly to the outlet openings 8 at the roof.

The advantages of these designs over other furnace structures known to applicant. are as follows: (l) more heat absorbing surface can be placed in a furnace of equivalent firebox volume, (2) the surface may be placed so that all tubes receive maximum benefit of the radiant heating surface, (3) no overhead or underground ue gas ducts are required, (4) preheated air may be directed to the burners with a minimum draft loss, and without the use of forced draft fans or extremely high stacks, (5) the furnace structure may be used to support the flue gas stack, (6) floor tubes are supported-by piers of refractory materiaLeliminating the use of alloy castings.

Both furnace designs are simple and economical to construct and repair, flexible and efficient in operation, highly efficient from the standpoint of utilization of re box volume and reduce the amount of critical material needed in construction.

Having thus described my invention, I claim: 1. A tube heater comprising a floor, a central inclined roof beams extending from the outer framework to the central framework and supported thereon at their respective ends, refractory linings mounted on the outer framework and the roof beams forming a furnace space, a pair of hollow refractory bridge walls terminating above said door, said bridge walls extending entirely across the furnace space, and being open to the exterior of said furnace space and open at their upper edges to provide for free circulation of air therethrough, a stack supported on said main beams in alignment with the flue formed by said bridgewalls, burners positioned to impinge their flames upon said bridgewalls, a convection tube bank in the passage between said bridgewalls, and radiant tube banks supported on said fioor and opposite the refractory linings for the roof and outer side walls.

2. In the combination of claim 1, windboxes into which the hollow spaces of the bridgewalls open at their upper edges, and said burners be- .ing positioned with respect to said windboxes so that preheated air from the bridgewalls is supplied to the flames of said burners.

3. A tube heater for fluids comprising in combination a furnace chamber having a floor, walls and roof, a pair of bridge walls extending from wall to wall across said chamber and from the roof downward in said chamber to a point adjacent said floor dividing said'chamber into two radiant heating sections and a central convection heating section in communication with both radiant sections, the roofs of the radiant heating sections being provided with inlets, at least one tube bank in each of said heating sections, an outlet in the upper portionv of said convection section, burners in said inlets disposed to direct flame and hot gases at an angle against the respective bridge wall to make the same radiant relative to the tube bank in said section, and a horizontal projection on the lower end of each of said bridge walls extending out into said radiant heating sections and disposed to create turbulence in the flame and hot gases from said burner whereby the heating of the radiant surfaces in said radiant sections is more uniform.

4. The combination of claim 3 in which said bridge Walls are hollow and in communication with the atmosphere and with said burners to supply air for combustion to said burners and at the same time cool the interior of said bridge walls.

LOUIS J. WEBER..

lmalrramiNoEs, CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number 

